U.S. Patent No. 4,745,836, issued May 24, 1988, to Dannenberg, describes a computer system which provides the ability to synchronize to and accompany a live performer. The system converts a portion of a performance into a performance sound, compares the performance sound and a performance score, and if a predetermined match exists between the performance sound and the score provides accompaniment for the performance. The accompaniment score is typically combined with the performance.
Dannenberg teaches an algorithm which compares the performance and the performance score on an event by event basis, compensating for the omission or inclusion of a note not in the performance score, improper execution of a note or departures from the score timing.
The performance may be heard live directly or may emerge from a synthesizer means with the accompaniment. Dannenberg provides matching means which receive both a machine-readable version of the audible performance and a machine-readable version of the performance score. When a match exists within predetermined parameters, a signal is passed to an accompaniment means, which also receives the accompaniment score, and subsequently the synthesizer, which receives the accompaniment with or without the performance sound.
While Dannenberg describes a system which can synchronize to and accompany a live performer, in practice the system tends to lag behind the performer due to processing delays within the system. Further, the system relies only upon the pitch of the notes of the soloist performance and does not readily track a pitch which falls between standard note pitches, nor does the system provide for the weighting of a series of events by their attributes of pitch, duration, and real event time.
Therefore, there is a need for an improved means of providing accompaniment for a smooth natural performance in a robust, effective time coordinated manner that eliminates the unnatural and "jumpy" tendency of the following apparent in the Dannenberg method.